Telephone system



April 10, 1928. I 1,665,231 M. B. STAZAK TELEPHONE SYSTEM 2 Sheet finest l April 10, 1928. v 1,665,231

M. B. STAZAK TELEPHONE SYSTEM Filed Oct. 29, 1924 2 Sheets-Sheet 2 Patented Apr. 10, 192 8.

7 AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, AooRPoRATIoN or, iLLIivors.

TELnrHoNE SYSTEM.

Application filed'ootober 29, 1924. Serial nopzaeasafl My invention relates to'telephone systems,

in which manual link or cord circuits are combined with a trunk circuit for the interconnecting of two telephone lines, and has 'to-do more riparticularly Wltll. the so-called prlvate branch exchange systems, such as areused in hotels, oflicebuildings, etc.

With the usual trunkcircuit, a -subscriber may make a number of calls without the panying drawings in which I illustrate my invention operating in, connectionwith a suitable telephone system; 1

F 1g. -1 shows, the calling. subscriber and cord circuit at the P. B. X., and Fig. 2 shows;

the trunk circuit to the main exchange and the connections to the .called subscriber.

In the drawings, I show a calling substationA and. a called substation D, the said calling ,anducalled substations'A andD connected, respectively, toline'circuits L and. L. The line clrcultsL and L comprise respec tively the usual line relays LR and LR,-cut- ,oit relays CO and CO, jacks J and J, and

'the line signals Sand S". The, jacks of the line circuit L are distributed among dii'ferent o erators )ositions and there is a line Si.-

nal S for each jack-so that when a call is I glllltlfltQCl over anyline, the line signals at "the various operators positions-are lighted,

and any one of a plurality of operators may seize the callto the exclusion of all the other operators. The line'circuit L has only one jack and is not multipled into different operators positions. I s

he cord circuit: C, inFigure 1, is provided with an answering plug AP and a'calling plug GP, the said answering 'and calling plugs AP and GP being connected by the heavily marked conductors. The answering end of the cord circuit C is provided with a combinedsleeve and link disconnectrelayLD which is energized when the answering plug AP is inserted into the 130k J of the calling line. The relay LD is provided with a high resistance winding and a low :resistance winding, and upon the actuation of the said relay LD, the high resistance winding is shunted and this prevents the relay L1) in line. The'relay AS upon' actuation, .'pre

'tothe energization of the relay AS to con- MICHAEL BQSTAZAK, or CHICAGO, ILLI NoIs'fAs's GNo'Rro ELL GG swrrorIBoAnD.

anoth'erxcord'from being'energized, should another operator attempt to 'ans'wer thecall after it has beenseized by an operator, so

that an operator at'any othe'r cord; attemptmg to seize the call after the first'operator has connected to the calling line, is prevented r from communicating with the subscriber.

The shunt of the 110w winding of-the relay LD'of the first cord prevents the-relayeLD- of the second cord from operating. As the said second operator is not connected to the calling line, 'dueto the relay LD of the sec- 1 ond cord remaining at normal, she does not "receive an answer from the callinglisub- I of her cord pair from'the connected'jack. I

scriber, and withdraws.the'answering plug.

Ananswering supervisory relay AS is provlded which is energized upon the action of LD, the said .relay' AS-operating over the vents the premature lighting of the" answering supervisory lamp AL. A listening relay LS is provided and is actuated in response nectthe operators set to the cord conductors.

..The callingend of the cord circuit c is i: 1 provided with a combined sleeve and link disconnect relay L'D actuated when the calling plug CPis inserted into the jack J? of the plug ended trunk circuit B. This re lay, upon energization, opens thecircuit'of keyv RKis provided for connecting anyone the listening relay. LS, which relay deener- 'gizing disconnects the operators set 1 0 from the cord connectors. A ipartyfllme rmging G depending upon the key plunger that is I depressed, to signal the called for subscriber i when connection is made directly toa called line. An interrupter relay IR is energized upon the actuation of the ringing key BK,

as the party line ringing. key RK is held in .the said .relay remaining energized as-long ring. The depression of the ringing key RK' and the operation of the relay LD. closes a circuit for the ringing control relay RC which relay RC controls the 'connection of ringing currents to the" called line, and also. connects the interrupter I to theinterrupter relay IR to intermittently energize and deenergize the said relay IR. A callin'g superactuated upon the response'of the called sub visor}, relay CS is also provided,"which'is relay LS, and the said relay restoring opens its alternate contacts and 21, to disconnect the operators set C from the cord conductors. The energization of the cut-oil relay CO prevents the actuation of the relay LR I and the.

premature lighting o'fthe lamp signal S I v 3 i The closing of alternate contact 19 of the relay LD" establishes a circuit for the calling supervisory lamp CL traced from battery through the calling supervisory lamp CL, normal c0nta'ct25 of the ringing controlrelay RC, conductors 26 and 27, nornial contact 28 of. the calling supervisory relay CS, conductors 29 and 30 to groundat alternate contact 19 of the relay LD, and th'e'said calling su-. pervisory lamp CL is lighted over this circuit and remains-lighted ,until the operator depresses the party line ringing key BK. The

operator havinginsertedthe plug G1? now depresses a ringing key plunger of the party V line ringing key BK- to its fully depressed position to closevthe end spring contacts 31 and 32Vand to 'connect oneflofdthe ringing generator G, G, G or G 'tosignal the operator. controlling the trunk circuit- 13.1 If the cord circuit Cwas used to connect directly to a called line the operator would select. the proper; frequency generator to signal the desired called lines. Theuclosing of alternate contact ofthe end springs of the party line ringingkey- RK- brings about the energization of the ringingcontrol relay RC during the interval that the key RK is held down, over .a circuittraced; from battery.

V- through the Winding of the ringing control relay RC, conductor '33, closed end spring contact 32, conductors d and 35, normal contact 36 of the disconnect control relay DCR, conductor 27 ,norma'l'contact 280i the call-w ingsupervisory relay CS, conductor 29 and 3010 ground at alternate contact 19 ofrelay 'LDr The closing of end spring contact 31 brings about the. energization of the interrupter relay IR during the interval that the ringing key BK is held down, over a circuit traced from battery through the upper winding of relay IR, conductor 37, alternate contact 38 oflthe relay RC, conductor 39 to ground atalternate contact 31 ofthe'end spring of the ringing key RK. Tlhe interrupter relay IR is energized over this circuit and the closing of alternate contact 40 oft-he said relay IR connects ringing current from one of the generators to signal the operator controlling the trunk c1rcu1t B.

The ringing control relay RC having been energized, due to the closure of the end spring contact 32, as already described, closes its alternate contact 41 to establish a locking circuit for itself traced from battery through the winding of the ringing control relay RC,

its alternate contact 41, conductors 34 and 85, normal contact '36 ofrelay DCR, conductor 27, normal contact 28 of relay CS, conalternate ductors 29 and30 to ground at alternate contact 19 of; the relay LD. The, opening of normal contact 25 of the relay RC now e fi aces the calling supervisory signal CL.

. glh'e closing of alternate contact 42 oztre- 'lay RC connects interrupter I to the lower winding of the interrupterrelayIR, the cir- 1 cult being traced atrom groundthrough the constantlyrotating interrupter I, alternate contact 42 of relay RC,-'conductor. l3 tofbattcry and-ground through the vlower winding connect ringing current to the trunk circuitv B over a path'traced fromthe ungrounded pole of the generator G, alternate contactoi'i I the depressed ringingkey plunger, conduo tor 45, alternate contact 40 of relayIR, tip contacts of the connected plug CP 'and jack J conductor 138, condenser 127, conductorv 101, Winding of relay E, conductor 1106, norcit-relay IR. The relay IR isintermittently I v energized anddeenergized over this circuit to \nalcontact 121,conductors' 153,139 and137,

quency. generator G which is of 16 cycles,

over conductor 18, throughhresistancee49, condenser 50, alternatev contact 47, of relay IR, conductor 51, alternate contact 52 of relay LD, alternate contact 11 of relay LD, tip contacts of the connected. plugoAPeand jack J, through'the receiver at the calling station '11, back through'ring contacts of the 1' connected plug AP andqjackd, alternate contact 12 of relay LD, conductor 13: andv tone justiraced gives the calling subscriber at the 'substat-ionA an audible s1gnal when, connection is made directly to a called linenotii'ying him that-the called subscriber is being signaled; v ,1

When the interrupter relay IR is ener gized, itattractsits alternate contacts-and allows ringing current to be sent through the trunk circuitas already described. Thus through the winding of the answering super- :7 I visory relay AS to battery and ground. This rela E is ener ized'when this rin 'in cur 7 L1 D t:

rent passes through it as already described.

When relay E is energized, it attracts its ar-" I mature 108, which allows alternate contact to drop down; this action causes the' line lamp signals S to be lighted over a circuit traced from battery through lamp signals S conductor 154, to ground, through alternate contact 110. This lamp remains lighted after relay E is deenergi- Zed-beeause' ot'the locking device preventing the return 1 of the armature lT-O-ltS normalpositron. q I

The operator notices the lighted lamp-sig nal S and presses the listening key LK thus and if it is, she inserts the. plugP into the connecting the operators set OS to the cord conductors. The operator inquires the wants ofthe calling subscriber, and assuming that the subscriber at substation D is the-party wanted, she ascertains if the line is idle,

jack J ofvthe line circuit L. She is not A 'connectedwith thetip circuit however un- Itilrelay F is'operated. When the listening key 'LK was *depressed,1a circuit for the energization of relayiF was established traoedlfrom battery through the. winding of relay F, normal contact 109 of relay E which Wasde energized when the interrupter relay IR was de-energized, (contact 109 followslthe operation" of. relay E independent i ofitslockingarmature) conductor 105, and

to ground through alternate contact 131.

of thelistening key LK. hen relay F is energized it restores alternate contact 110 'to its normal position, thus ,efl'acing the lamp signal S; it also prevents vthe premature lighting of the lamp signal S I Assuming that the listening key was depressed when the interrupter relayIR was de-energized, a circuit fortheenergization of relay M, in the trunk circuit B, and relay CS, insthe cord circuitLC, is established traced from 1 battery through the lower winding of the relay CS, conductor 7 0, alternate contact 71, normal contact 46, ring contacts oftthe connected plug CPa'nd jack J conductors 137, 139, 153' and 160, through the winding of i relay vM, over conductor 146, alternate contact 128 of the listening key' I LK, conductor158, 140 and 138, through 40- ing of the calling supervisory relay GS. The operator having inserted the plug P tip contacts of the connected plug CP-and" jack J normal contact 40 of relay IR, al-. ternatecontact 65 of relay LD, and con-' ductor 72 to ground through the upper wind- 1 into thejack J as before described now tact 131 of the kev'LK.

alternate contact 1280f the key LK opens restores her listening 'key v LK. This restoration of thellist'ening key LK opens the energizat ing for relav F at alternate con- The opening of theinitial energizing circuit of relay M but relay M being slow to release due to the shunt about its winding is held momentarily energized until the normal contact 120 of relay F closes at which time relay'M establishes a locking circuit for itself, through its alternate contact 123, by current flowing from battery to the'winding of relay M,

as previously described, through alternate contact 123,conductor 145, normal contact 161' of the release key. R, conductor 142, normal contact 120 conductors 107, 140 and 138,

through the connected plug GP and jack J 2 to ground at the'CS relay, as previously vdescribed. The opening of normal contact '28 of relay Gs jopensthe locking circuit of the ringing control relay RC, which relay deenergizesto open its alternate contact 42, iwhich disconnects the ringing interrupter I fromthe lower winding of the relay IR;

The relay IR now remains at'normal, and

the opening of its alternate contact 40 pre-.

vents further application of ringing current V to the trunk circuit.

jack J ,,a circuit is established forthe energiz ation ofrelay H and relay CO of the' line circuit L, by current flowing from bat-- VVhen. the operator inserts plug P into teryjthrough the Winding'of'relay H, conductor 152, connected plug P and jack J to ground through the cut-off relay CO.

When relay CO is energized, the alternate contacts 2 and 370i said relay, COare at tracted, thus connecting the subscribers set at D to the exchange. The operator now i I i I depresses the ringing key R, of the trunk circuit B, and a circuit is-established for the ringing of the callbell at subscriberssta tion Dyover a path traced from the ungrounded side of the ringing generator Gr through alternate contact 163of said'ringing key R, over conductor 155, through the tip contacts ofthe connected plug P and jack J, alternate contacts 3 ofthe cut-ofi relay 00, through the condenser, switchhook, and call bell of the subscribers stationD, and back through alternate contact .2 ofthe relay CO, rinu contacts of the connected plug P and ackJhto ground at alternate contact I 1640f the ringing key, R. The call bell at substation D" rings, over the circuit just traced, and: the subscriber at D removes his receiver fromthe switchhook. .7 g 5 Assuming that the subscriber jat-substation D removes his :receiverfrom the switchhook when the ringing key R is in its normal position, a circuit for the energization of relay N will be established by current flowing from battery through the lower winding of relay CS, conductor70, alternate contact 71, of 'relayYLD, normal contact 46 of relay IR, through the ring contacts of, the connected plug CP and jack J conductors 137 139 and 165, the winding of relay N, conductors 159 and 151, normal contact ground through the upper Winding of re- I lay CS; The energization of relay N establishes a circuit for the'actuation of relay F traced from battery through the WlIlding of relay F, normal contact 109 of relay E, conductors 105 and 166, alternateoperator that the called subscriber at substation D has answered. Following said information, the operator will desist rromdepressing rin'ging key R and thus'actuating said callbellat substation D. Also when relay F is actuated,a circuit for the enerseries energizing circuit of the relay LD and relay CO is interrupted atthe' contact '8 of gization'of relay K is established by current flowing from battery, through the Wind ing of said "relay K, alternate contact 119 of relay 1, and over conductor 1 11 to ground at alternate contact1-18 of relay'I-I. Relay K locks itself by a circuit through its alternate contact 115, traced from :battery, throughsaid relay K alternate contact 115 and conductors 166, 1 13" and 141- to ground at alternate contact 118 of relay 'H; The.

actuation of relay 'F breaks the locking circuit of relay M, at its alternate contact 120, thereby causing the derenergizationof relay M, which returns to no'rmalJ Relay GS of cord circuit C is now held up over the called line. 4

lVhen the operator releases the-ringing key R andthe'called subscriber at substation'D removes the receiver fromthe switchhook, a talking circuit. is established from substation A to substation D over the heavy conductors and the called and'calling subscribers may carry on a-conversation.

After the subscribers have finished their conversation, they replace their receivers on their respective switchhooks, causing the answering and callingsupervisory relays AS and CS to restore, due to the opening of the switchhook contacts at the respective stations. A and Dr The closing of normal contacts 15 and'54 ofthe respective supervisory relays ASand CScloses an energizing cir cuit for the disconnect control relay DOB,

traced from'battery through the winding of relay DCR, conductor 53, normal contact-54 of the calling supervisory relay CS, conductor 55, normal contact 15 of the answering supervisory relay AS, conductor 56, alternate contact 57 of the relay LD, con-' duct-or 30, to ground at'altern-ate contact 19 of the relay LD. The relay DCR upon energization opens its-normal contacts 8 and 23 and the opening of normal contact 8 in- 'terrupts the energizing circuit of the relay- LD, and the opening ofnormal-contact 23;

station D, as to its idle or busy condition,

opens the energizingfcircuit of relay LD,

and the two relays LD and LD now restore to normal. The rela'ysLD andLD open their respective contacts 57 and 19, opening momentarily held energized until a locking circuit is establishedfor it, which may now be traced-from battery throughthe winding" of relay DCR, its alternate contact'60, conductor 61, normal contact 62 of relay 63, conductor 64:, normal contact ofrelay LD, normal contact 40 of relay IR, tip contacts of'the connected plug 0]? and jack J nors inal contact 133 or relay CO said relay CO having restored to normal when the series energizingcircuit of the relays LD and CO V was interrupted at contact 23 upon the energization of relay DGRftogroundIThe the energized relay DC R, and relays LD and CO restore. The relay L D upon restoration opens its'alternate contacts 11 and 12, disassociat-ing the calling line rrom the strands of the link or cord circuit C, and the restoration of relay LD opens'its alternate contacts 52 and 71, disassociating thecalled line from the strands of the cord circuitO. The closing of alternate contact 36 of the relay DCR establishes a circuit for the calling supervisory lamp CL traced from battery through the lamp CL, normal contact 25 of relay RC, conductors 26 and,27' to-gro'und "at alternate contact 36 of relay"DGB,Yand 5 the lamp CL-is'thus lighted over this circuit.

A circuitis' also established for thelighting of the answering supervisory lamp 'AL,

conductor 55, norinal'cont-act5 1 of relay CS, conductor 53, alternate contact 60' of relay traced from battery through the lamps AL,

hm DOB, conductor61, normal contact62 o'rrelamp AL is thus lighted overlthis circuit.

The closing'of alternateco'ntact 23 ot'relay .DQR connects relay'63 over conductor'24; to

the sleeve of the connected jack J but relay 63 is not energized at' this'ltiin'e, asground from thesleeve of the connected jack J extends over the sleeve contact of the plug.

CP over conductor 24 andthrough alternate contact 23 of relay DCR to-one terminal of the winding'ofrelay "63 which is also conjnected to ground. The ground potential upon the sleeve of the jacks J 2 prevents the sleeves of thekjacksJ' from testing busy when the subscribers have replaced their receivers and the plugs AP and GP, are still connected injfth'e' respective jacks J and J so that should another operator test the line o'fsub:

should an operator be busy in handling other,

connections andjpe'rmit'the plugs'AP and GP to remain in the jacks, the-lines are in;-

,me'diatelyavailable as called lines and will testidle. r

The operator noting the two lighted supervisory signals AL and GL removes the answeringplug AP and calling plug GP from Q their respective jacks J and J and the removal of calling plug GP from jack J of the i, called line opens the energizing circuit of -the disconnect relay DGR at the tip coni it ' i the plugAPjI-om the jack J ofthe calling tacts of theplug GP andrjack J and the relay DGR, upon de-energization, opens its alternatecontacts (Hand 36', which opens the circuits of the; answering and calling supervisory signals AL and GL, respectively, thus efiacing the two signals. The removal of line disconnects the answering end of the cordcircuit- G from the calling'line, andthc apparatus used in establishing a connection between the calling subscriber atsubstation A and the'calledsubscriberat substation D is now at normal andavailable for estab-,

lishing; other connections.

f lVhen the subscriber atD finishes hisconversation, and replaces l11S receiver on the switchhook, the circuit for the energization of relay N is interrupted at the switch-I V hookof substation D. The relay N- being tie-energized, it open its alternate con- {tact 125' and this interrupts thecircuit for the'energization of; relay F, allowingf'it to become-normal andthus open its alternate contacts. .This action establishes :a circuit for theenergization of relay Lrby. current flowing from. battery throughthe Winding ofrelay L, conductor104, alternate con tact 116 of relay K, conductor 102, alternate contact 117,- conductors -149and 103, normal, contact 124 of relay M, normal contact 125, of'relay N, and through conductors 14341116, 141 totground at alternate contact 118 of-,-relay H. g The ,lamp signal S is lightediwhen normal contact 119 of a relay F is returned' to its normal position establishinga circuit from-batterythrough the lamp-signal-s normalrontactjllt), conduc-v tor ltl'to of relay H.

groundat alternate contact 118 7 When the operator; sees the lamp burning she; knows thatthe subscribers have finished their conversation, and accordingly, she

withdrawsplug P from j ack J thus cutting off the called subscriber from the interconnecting trunk 1 and cord circuits. 7 Then; the

plug is withdraw-n, the circuit for the energization of cutoil relay GO and relay it His interrupted. This restores the alternate contacts 2" and 3 .of the said-cut-ofi relay GO -to their normal positions. The de- 60 energization f of: relay H 7 causes the; resto= ration of alternate contacts 117' and: 1118" of saidi'relay H to' their normal positions, thus breaking? the energizing" circuitsfor relay K and relay L, which restore to tl1eir;normal positions- Thelamp'signal' S Was ef-" see-5 ,2

faced by the interruption of its up energizing circuit at normal cont-act 118 of relay 7H,

When the subscribers place their respective receivers on the switchhooks, the cord circuit C is immediately ready foruse by;

new subscribers, or a new call initiated by one of the parties of the formerconversttion. If the cord circuit G Was used .for direct connection to a called subscr1bers line and the parties had replaced their receivers, it the called party was to make a recall and the call answered by a difierentoperator, when she plugs into a multiple jackof the called line she would operate relay 63 and transfer the ground-supply. for lamp AL from relay GO to alternate contact 62; of relays 63. v -Assumingthat subscriber D is in a hotel that charges him a certain amount for each outgoingcallhe makes, before the'operator .Who mightbe busy handling other calls,

could withdrawthe plug P from jackJ, the subscriber at D could make a numberof calls, and thereby make thehotel lose a certain amount of revenue. In order to prevent this from happening, I have provided means inthe trunk eircuit to dis'connect the: trunk circuit from the cord circuit} immediately 'upon the replacing of the receiver on'the switchhook.

,Assuming thatthe'subscriber'D has just finished a'conversation, and replaced therescribers set and back through alternate con? tact 3 of cut-oft; relay GO, tip contacts of ceiver on the switchhook, and then decides a contact 2 of relay GO, through the subconnected plug P and jack'J, normal'contact 163 of ringing'key' R, conductor 140,

alternate contact 111, to ground, through winding of coil 11.L- The energization of relay N-establishes acircuit for the actuation ofrela'y F whichiniturnopens the circuit of lamp signal S te 'eflace thev same as has been; previouslydescribed. The? relay Lbeing energized holds the circuit open and prevents the calling subscriber at D from gettingra connection with the cord circuit G.

The I operator controlling the' trunk 1 circuit B seeingithe lamp signal S eifaced depresses thereleasekey-R" which interrupts the cir-' cuit for the 'energ-ization'otrelay L at alternate contacts- 161 and "162'; said relay L de-energiizing" closes the talking, circuit P and jack J, alternatecontact 2 of relay CO, subscribers set at D, alternate contact .3 of cut-off relay CO, connected plug? and jack J, conductor 155, normal contact 163 of ringing key R, conductors 140 and 138- alternate contact 133 of relay CO to ground. This establishes aeircuit for. the lighting of lamp signal S. by a circuit traced from bat- .tery through the lamps S and alternate contact 132, of relay LE to ground. 1 The operator controlling the cord circuit C notices the lighted lamp S and plugs an answering plug AP into jack J and the call is taken care of in the'usual way.

Having described my invention operating with a certain circuit arrangement, I- do not wish to be limited or to the same, as changes and modifications may readily suggest themselves to those skilled in the art, and I, therefore, aim to coverall such changes and modifications as come Within the spirit and scope of the appended claims. 7

Having described my invention what I claiinas new and desire to secure by Let? ters Patent isz i 1. A telephone system including'a calling subscribers line and a called subscribers line, a cord circuit and a two-waytrunkcircuit for connecting said line s, disconnect means for automatically disconnecting said cord circuit from the trunk circuit, recall means in said trunk circuit controlled by the called subscriber, and trunk operator controlled means for releasing said recall means permitting the operation of a signal associated with said trunk circuit to signal the operator associated with said cord circuit.

2. A telephone system including a calling.

subscribers line and a called subscribers line, a cord circuit and a trunk circuit for effecting connection between said lines, link disconnect means in said cordcircuit and controlled by said calling subscriber for automatically disconnecting said cord circuit from said trunk circuit, and disconnect means in said trunk for preventing an ex-' tension of a recall from said called line over the trunk circuit to the operator associated with said cord circuit and means in said trunk circuit under the control of the trunk operator associated with said trunk circuit for releasing said disconnect means to permit said recall to be extended to the operator of said cord circuit.

3. A telephone system including a calling subscribers line and a called subscribers line, a cord circuit and a trunk circuit for effecting connection between said lines, dis

connect means for automatically disconnect ing said cord circuit from said trunk circuit,

disconnect means in said trunk circuit for preventing an extension of a call over the trunk circuit to theoperator associated with said cord circuit, and trunk operator control means for rendering ineflective said last means to permit theeXtensionofa call to the; cord operator.

4. The combination of a cord'circuit and a a two-way trunk circuit connecting a pair or" lines in conversational circuit as call ng. and

called lines, subscriber controlled means for disconnecting the cord circuit from the trunk circuit, and called subscriber controlled means :for disconnecting one end of the trunk circuit from the other end thereof, and a pair of signals for said trunk circuit,- one directly controlled by said calledsubscriber and said other signal adapted to be placed under the control of saidscalled subscriber by operator controlled switchingmeans in said trunk circuit. 1 p 5. The combination of a cord circu t'and a two-way trunk circuit connectinga pair oi connecting the cordcircuit from one of said lines and fromthe trunk circuit and for disconnecting one end of the trunk circuit from r the other end thereof, and a pair ofsignals directly controlled by one of saidsubscribers and the otherof said pair'of signals be ing placed under the control of said one of said subscribers by operator controlled switching means in said trunk'circuit.

6. The combination of a pair of subscribers l nes connected by means of'a cord ci'r cuit and a two-way. trunk circuit, disconnect means for disconnecting the cord "circuit from the trunk circuit and for disconnecting the outgoing end of the trunk circuit from'the incoming end thereof, a signal associated with said trunk directly controlled by said one of said subscribers, and a second signal at the incoming end of said trunk circuit placed under the control of the said one of said subscribers by operator controlled switching means in said trunk circuit;

7 A telephone system including a twoway trunkcircuit for connecting subscribers lines, and disconnect means for disconnecting one end of said trunk circuit from the other end thereof while a subscribers line remains connected to the trunk circuit, and

a signal for said trunk circuit adapted to be placed under the control of said subscr bers line, by operators switching said trunk circuit.

8. A telephone system including a twomeans in way trunk circuit for connecting subscrib-,

subscribers lines, disconnect neans for disassociated with said trunk circuit, one being ice ins

signalby said subscriber and switching said controlled means for restoring the said di'sconnect means to perm t the trunk circuit to beused for other calls while said'trunk circuit is connected to saidsubscribers line,

and a signal for saldtrunk circuit adapted robe-placed under the control of said connected -subscriber sline by said operator controlled means insaid trunk circuit.

9. A telephone system including a two-way trunk circuit connected to asubscribers line,

a signal associated with one end of said trunkcircuit, subscriber controlled means for preventing said subscriber from operating saidsignal, and operator controlled restoring means in said trunk for replacing the con trol of said signal under said subscriber prior to the disconnection of said trunk from said subscribers line. I

control to the other of said signals prior to the disconnection of said trunk-1 from said subscribers line. f

11. A telephone system including acalli'ng subscribers line anda called subscribers line, a cord circuit and a trunk circuit for connecting said lines, a battery supply relay insaid cord circuitfor supplying said called fsubscribers line With the talking current, a

battery supply relay in said tiunlzcircuit,

and subscriber controlled means for switching the supply of talking current from said relay in said cord circuit to said relay in said trunk circuit, and operator controlled means for releasing said battery'supply relay in said trunk circuit prior to the disconnection of said trunk from said called tor, a's'ignal for said trunk circuit'controllable by one of said subscribers, and a third signal for said trunk circuit to which the trunkoperatorscan switch said subscribers control. v v A 14. A telephone'systenr including a calling subscribers line, anda called subscribers line, a cord circuits-and atrunk circuit for connecting said line's, link disconnect means in said cord circuit controlled by said calling subscriber for automatically disasse- .ciating saidco'rd' circuit from the trunk circuit, andirecall means associated only with said trunk circuit and controlled" by the called subscriber for signalling the operator associated with the incoming end of the trunk circuit. r

Signed by me. at Chicago,]in"tl1e county of Cook an d' Sta te of Illinois, this' 27th day otOctober, 1924; I

MICHAEL 13-. sTirZAK. 

